The proposed research will examine the characteristics of taste-responsive neurons in the central nervous system of the hamster. In either pentobarbital anesthetized or unanesthetized acute preparations, neurons in the nucleus tractus solitarius, parabrachial region of the pons, ventrobasal thalamus, and cortical gustatory projection, will be recorded using a wide range of stimuli and employing cross-adaptation procedures, taste-modifying drugs, and taste mixtures. Gustatory projections into the ventral forebrain of the hamster will also be examined electrophysiologically in acute preparations. Behavioral studies with hamsters will be done to assess the similarity of taste stimuli along several qualitative dimensions, to derive an hedonic ordering among them, and to observe the behavior of hamsters to a wide variety of naturally occurring foods. Chronic techniques for recording unit activity in freely behaving animals will be applied to central gustatory relays in rats and hamsters.